• [DLA 4168-1] openafs security update of three CVEs related to theft of credentials, crashes or buffer overflows.
• [DLA 4196-1] kmail-account-wizard security update to fix one CVE related to a man-in-the-middle attack when using http instead of https to get some configuration.
• [DLA 4198-1] espeak-ng security update to fix five CVEs related to buffer overflow or underflow in several functions and a floating point exception. Thanks to Samuel Thibault for having a look at my debdiff.
• [#1106867] created Bookworm pu-bug for kmail-account-wizard. Thanks to Patrick Franz for having a look at my debdiff.

• [ELA-1444-1] kmail-account-wizard security update to fix two CVEs in Buster related to a man-in-the-middle attack when using http instead of https to get some configuration. The other issue is about a misleading UI, in which the state of encryption is shown wrong.
• [ELA-1445-1] espeak-ng security update to fix five CVEs in Stretch and Buster. The issues are related to buffer overflow or underflow in several functions and a floating point exception.

• indi-eqmod
• supernovas (sponsored upload)

• smstools

• greylist
• setserial
• mlat-client-adsbfi
• pkcs11-proxy

1. Security audit of Reproducible Builds tools published
2. When good pseudorandom numbers go bad
3. Academic articles
4. Distribution work
5. diffoscope and disorderfs
6. Website updates
7. Reproducibility testing framework
8. Upstream patches

Security audit of Reproducible Builds tools published The Open Technology Fund s (OTF) security partner Security Research Labs recently an conducted audit of some specific parts of tools developed by Reproducible Builds. This form of security audit, sometimes called a whitebox audit, is a form testing in which auditors have complete knowledge of the item being tested. They auditors assessed the various codebases for resilience against hacking, with key areas including differential report formats in diffoscope, common client web attacks, command injection, privilege management, hidden modifications in the build process and attack vectors that might enable denials of service. The audit focused on three core Reproducible Builds tools: diffoscope, a Python application that unpacks archives of files and directories and transforms their binary formats into human-readable form in order to compare them; strip-nondeterminism, a Perl program that improves reproducibility by stripping out non-deterministic information such as timestamps or other elements introduced during packaging; and reprotest, a Python application that builds source code multiple times in various environments in order to to test reproducibility. OTF s announcement contains more of an overview of the audit, and the full 24-page report is available in PDF form as well.

When good pseudorandom numbers go bad Danielle Navarro published an interesting and amusing article on their blog on When good pseudorandom numbers go bad. Danielle sets the stage as follows:

[Colleagues] approached me to talk about a reproducibility issue they d been having with some R code. They d been running simulations that rely on generating samples from a multivariate normal distribution, and despite doing the prudent thing and using set.seed() to control the state of the random number generator (RNG), the results were not computationally reproducible. The same code, executed on different machines, would produce different random numbers. The numbers weren t just a little bit different in the way that we ve all wearily learned to expect when you try to force computers to do mathematics. They were painfully, brutally, catastrophically, irreproducible different. Somewhere, somehow, something broke.

Thanks to David Wheeler for posting about this article on our mailing list

Academic articles There were two scholarly articles published this month that related to reproducibility: Daniel Hugenroth and Alastair R. Beresford of the University of Cambridge in the United Kingdom and Mario Lins and Ren Mayrhofer of Johannes Kepler University in Linz, Austria published an article titled Attestable builds: compiling verifiable binaries on untrusted systems using trusted execution environments. In their paper, they:

present attestable builds, a new paradigm to provide strong source-to-binary correspondence in software artifacts. We tackle the challenge of opaque build pipelines that disconnect the trust between source code, which can be understood and audited, and the final binary artifact, which is difficult to inspect. Our system uses modern trusted execution environments (TEEs) and sandboxed build containers to provide strong guarantees that a given artifact was correctly built from a specific source code snapshot. As such it complements existing approaches like reproducible builds which typically require time-intensive modifications to existing build configurations and dependencies, and require independent parties to continuously build and verify artifacts.

The authors compare attestable builds with reproducible builds by noting an attestable build requires only minimal changes to an existing project, and offers nearly instantaneous verification of the correspondence between a given binary and the source code and build pipeline used to construct it , and proceed by determining that t he overhead (42 seconds start-up latency and 14% increase in build duration) is small in comparison to the overall build time.
Timo Pohl, Pavel Nov k, Marc Ohm and Michael Meier have published a paper called Towards Reproducibility for Software Packages in Scripting Language Ecosystems. The authors note that past research into Reproducible Builds has focused primarily on compiled languages and their ecosystems, with a further emphasis on Linux distribution packages:

However, the popular scripting language ecosystems potentially face unique issues given the systematic difference in distributed artifacts. This Systemization of Knowledge (SoK) [paper] provides an overview of existing research, aiming to highlight future directions, as well as chances to transfer existing knowledge from compiled language ecosystems. To that end, we work out key aspects in current research, systematize identified challenges for software reproducibility, and map them between the ecosystems.

Ultimately, the three authors find that the literature is sparse , focusing on few individual problems and ecosystems, and therefore identify space for more critical research.

Distribution work In Debian this month:

• Ian Jackson filed a bug against the debian-policy package in order to delve into an issue affecting Debian s support for cross-architecture compilation, multiple-architecture systems, reproducible builds SOURCE_DATE_EPOCH environment variable and the ability to recompile already-uploaded packages to Debian with a new/updated toolchain (binNMUs). Ian identifies a specific case, specifically in the libopts25-dev package, involving a manual page that had interesting downstream effects, potentially affecting backup systems. The bug generated a large number of replies, some of which have references to similar or overlapping issues, such as this one from 2016/2017.
• Chris Hofstaedtler filed a bug against the metasnap.debian.net service to note that some packages are not available in metasnap API.
• 22 reviews of Debian packages were added, 24 were updated and 11 were removed this month, all adding to our knowledge about identified issues.

Hans-Christoph Steiner of the F-Droid catalogue of open source applications for the Android platform published a blog post on Making reproducible builds visible. Noting that Reproducible builds are essential in order to have trustworthy software , Hans also mentions that F-Droid has been delivering reproducible builds since 2015 . However:

There is now a Reproducibility Status link for each app on f-droid.org, listed on every app s page. Our verification server shows or based on its build results, where means our rebuilder reproduced the same APK file and means it did not. The IzzyOnDroid repository has developed a more elaborate system of badges which displays a for each rebuilder. Additionally, there is a sketch of a five-level graph to represent some aspects about which processes were run.

Hans compares the approach with projects such as Arch Linux and Debian that provide developer-facing tools to give feedback about reproducible builds, but do not display information about reproducible builds in the user-facing interfaces like the package management GUIs.
Arnout Engelen of the NixOS project has been working on reproducing the minimal installation ISO image. This month, Arnout has successfully reproduced the build of the minimal image for the 25.05 release without relying on the binary cache. Work on also reproducing the graphical installer image is ongoing.
In openSUSE news, Bernhard M. Wiedemann posted another monthly update for their work there.
Lastly in Fedora news, Jelle van der Waa opened issues tracking reproducible issues in Haskell documentation, Qt6 recording the host kernel and R packages recording the current date. The R packages can be made reproducible with packaging changes in Fedora.

diffoscope & disorderfs diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb made the following changes, including preparing and uploading versions 295, 296 and 297 to Debian:

• Don t rely on zipdetails --walk argument being available, and only add that argument on newer versions after we test for that. [ ]
• Review and merge support for NuGet packages from Omair Majid. [ ]
• Update copyright years. [ ]
• Merge support for an lzma comparator from Will Hollywood. [ ][ ]

Chris also merged an impressive changeset from Siva Mahadevan to make disorderfs more portable, especially on FreeBSD. disorderfs is our FUSE-based filesystem that deliberately introduces non-determinism into directory system calls in order to flush out reproducibility issues [ ]. This was then uploaded to Debian as version 0.6.0-1. Lastly, Vagrant Cascadian updated diffoscope in GNU Guix to version 296 [ ][ ] and 297 [ ][ ], and disorderfs to version 0.6.0 [ ][ ].

Website updates Once again, there were a number of improvements made to our website this month including:

• Chris Lamb:
  • Merged four or five suggestions from Guillem Jover for the GNU Autotools examples on the SOURCE_DATE_EPOCH example page [ ]
  • Incorporated a number of fixes for the JavaScript SOURCE_DATE_EPOCH snippet from Sebastian Davis, which did not handle non-integer values correctly. [ ]
• David A. Wheeler:
  • Fix an apostrophe in the README.md file. [ ]
• Hans-Christoph Steiner:
  • Add the F-Droid Verification Server to the Tools page. [ ]
  • Add the Creative Commons Attribution-ShareAlike 4.0 International as the website s root LICENSE file. [ ]
  • Updated the Recording the build environment page to add a section pertaining to how F-Droid handles this. [ ]
• Jochen Sprickerhof:
  • Add Chris Hofstaedtler to the Who is involved? page. [ ]
• Sebastian Davids:
  • Fix the CoffeeScript example on the SOURCE_DATE_EPOCH page. [ ]
  • Remove the JavaScript example that uses a fixed timezone on the SOURCE_DATE_EPOCH page. [ ]

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework running primarily at tests.reproducible-builds.org in order to check packages and other artifacts for reproducibility. However, Holger Levsen posted to our mailing list this month in order to bring a wider awareness to funding issues faced by the Oregon State University (OSU) Open Source Lab (OSL). As mentioned on OSL s public post, recent changes in university funding makes our current funding model no longer sustainable [and that] unless we secure $250,000 in committed funds, the OSL will shut down later this year . As Holger notes in his post to our mailing list, the Reproducible Builds project relies on hardware nodes hosted there. Nevertheless, Lance Albertson of OSL posted an update to the funding situation later in the month with broadly positive news.
Separate to this, there were various changes to the Jenkins setup this month, which is used as the backend driver of for both tests.reproducible-builds.org and reproduce.debian.net, including:

• Migrating the central jenkins.debian.net server AMD Opteron to Intel Haswell CPUs. Thanks to IONOS for hosting this server since 2012.
• After testing it for almost ten years, the i386 architecture has been dropped from tests.reproducible-builds.org. This is because that, with the upcoming release of Debian trixie, i386 is no longer supported as a regular architecture there will be no official kernel and no Debian installer for i386 systems. As a result, a large number of nodes hosted by Infomaniak have been retooled from i386 to amd64.
• Another node, ionos17-amd64.debian.net, which is used for verifying packages for all.reproduce.debian.net (hosted by IONOS) has had its memory increased from 40 to 64GB, and the number of cores doubled to 32 as well. In addition, two nodes generously hosted by OSUOSL have had their memory doubled to 16GB.
• Lastly, we have been granted access to more riscv64 architecture boards, so now we have seven such nodes, all with 16GB memory and 4 cores that are verifying packages for riscv64.reproduce.debian.net. Many thanks to PLCT Lab, ISCAS for providing those.

Outside of this, a number of smaller changes were also made by Holger Levsen:

• reproduce.debian.net-related:
  • Only use two workers for the ppc64el architecture due to RAM size. [ ]
  • Monitor nginx_request and nginx_status with the Munin monitoring system. [ ][ ]
  • Detect various variants of network and memory errors. [ ][ ][ ][ ]
  • Add a prominent link to reproducible-builds.org. [ ]
  • Add a rebuilderd-cache-cleanup.service and run it daily via timer. [ ][ ][ ][ ][ ]
  • Be more verbose what sources are being downloaded. [ ]
  • Correctly deal with packages with an epoch in their version [ ] and deal with binNMUs versions with an epoch as well [ ][ ].
  • Document how to reschedule all other errors on all archs. [ ]
  • Misc documentation improvements. [ ][ ][ ][ ]
  • Include the $HOSTNAME variable in the rebuilderd logfiles. [ ]
  • Install the equivs package on all worker nodes. [ ][ ]
• Jenkins nodes:
  • Permit the sudo tool to fix up permission issues. [ ][ ]
  • Document how to manage diskspace with OpenStack. [ ]
  • Ignore a number of spurious monitoring errors on riscv64, FreeBSD, etc.. [ ][ ][ ][ ]
  • Install ntpsec-ntpdate (instead of ntpdate) as the former is available on Debian trixie and bookworm. [ ][ ]
  • Use the same SSH ControlPath for all nodes. [ ]
  • Make sure the munin user uses the same SSH config as the jenkins user. [ ]
• tests.reproducible-builds.org-related:
  • Disable testing of the i386 architecture. [ ][ ][ ][ ][ ]
  • Document the current disk usage. [ ][ ]
  • Address some image placement now that we only test three architectures. [ ]
  • Keep track of build performance. [ ]
• Misc:
  • Fix a (harmless) typo in the multiarch_versionskew script. [ ]

In addition, Jochen Sprickerhof made a series of changes related to reproduce.debian.net:

• Add out of memory detection to the statistics page. [ ]
• Reverse the sorting order on the statistics page. [ ][ ][ ][ ]
• Improve the spacing between statistics groups. [ ]
• Update a (hard-coded) line number in error message detection pertaining to a debrebuild line number. [ ]
• Support Debian unstable in the rebuilder-debian.sh script. [ ] ]
• Rely on rebuildctl to sync only arch-specific packages. [ ][ ]

Upstream patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. This month, we wrote a large number of such patches, including:

• Bernhard M. Wiedemann:
  • cmake/musescore
  • netdiscover
  • autotrace, ck, cmake, crash, cvsps, gexif, gq, gtkam, ibus-table-others, krb5-appl, ktoblzcheck-data, leafnode, lib2geom, libexif-gtk, libyui, linkloop, meson, MozillaFirefox, ncurses, notify-sharp, pcsc-acr38, pcsc-asedriveiiie-serial, pcsc-asedriveiiie-usb, pcsc-asekey, pcsc-eco5000, pcsc-reflex60, perl-Crypt-RC, python-boto3, python-gevent, python-pytest-localserver, qt6-tools, seamonkey, seq24, smictrl, sobby, solfege, urfkill, uwsgi, wsmancli, xine-lib, xkeycaps, xquarto, yast-control-center, yast-ruby-bindings and yast
  • libmfx-gen, libmfx, liboqs
• Chris Hofstaedtler:
  • #1104578 filed against jabber-muc.
• Chris Lamb:
  • #1105171 filed against golang-github-lucas-clemente-quic-go.
• Jelle van der Waa:
  • gitlab-shell
• Jochen Sprickerhof:
  • #1104965 filed against bootp.
• Zhaofeng Li:
  • Add support for --mtime and --clamp-mtime to bsdtar.
• James Addison:
  • #1105119 for python3 requested enabling a LTO-adjacent option that should improve build reproducibility.
  • #1106274 upstream fix merged for freezegun for a timezone issue causing unit tests to fail during testing.
  • Opened a pull request for tutanota in an attempt to resolve a long-standing reproducibility issue.
• Zbigniew J drzejewski-Szmek:
  • 0xFFFF: Use SOURCE_DATE_EPOCH for date in manual pages.

Finally, if you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

• IRC: #reproducible-builds on irc.oftc.net.
• Mastodon: @reproducible_builds@fosstodon.org
• Mailing list: rb-general@lists.reproducible-builds.org

A Broken Ecosystem The Kubernetes packaging situation in Debian had been problematic for some time. Given its large codebase and complex dependency tree, the initial packaging approach involved vendorizing all dependencies. While this allowed a somewhat functional package to be published, it introduced several long-term issues, especially security concerns. Vendorized packages bundle third-party dependencies directly into the source tarball. When vulnerabilities arise in those dependencies, it becomes difficult for Debian s security team to patch and rebuild affected packages system-wide. This approach broke Debian s best practices, and it eventually led to the abandonment of the Kubernetes source package, which had stalled at version 1.20.5. Due to this abandonment, critical bugs emerged and the package was removed from Debian s testing channel, as we can see in the package tracker.

---

New Debian Kubernetes Team Around this time, I became a Debian Maintainer (DM), with permissions to upload certain packages. I saw an opportunity to both contribute more deeply to Debian and to fix Kubernetes packaging. In early 2024, just before DebConf Busan in South Korea, I founded the Debian Kubernetes Team. The mission of the team was to repackage Kubernetes in a maintainable, security-conscious, and Debian-compliant way. At DebConf, I shared our progress with the broader community and received great feedback and more visibility, along with people interested in contributing to the team. Our first tasks was to migrate existing Kubernetes-related tools such as kubectx, kubernetes-split-yaml and kubetail into a dedicated namespace on Salsa, Debian s GitLab instance. Many of these tools were stored across different teams (like the Go team), and consolidating them helped us organize development and focus our efforts.

---

De-vendorizing Kubernetes Our main goal was to un-vendorize Kubernetes and bring it up-to-date with upstream releases. This meant:

• Removing the vendor directory and all embedded third-party code.
• Trimming the build scope to focus solely on building kubectl, Kubernetes CLI.
• Using Files-Excluded in debian/copyright to cleanly drop unneeded files during source imports.
• Rebuilding the dependency tree, ensuring all Go modules were separately packaged in Debian.

We used uscan, a standard Debian packaging tool that fetches upstream tarballs and prepares them accordingly. The Files-Excluded directive in our debian/copyright file instructed uscan to automatically remove unnecessary files during the repackaging process:

$ uscan
Newest version of kubernetes on remote site is 1.32.3, specified download version is 1.32.3
Successfully repacked ../v1.32.3 as ../kubernetes_1.32.3+ds.orig.tar.gz, deleting 30616 files from it.

The results were dramatic. By comparing the original upstream tarball with our repackaged version, we can see that our approach reduced the tarball size by over 75%:

$ du -h upstream-v1.32.3.tar.gz kubernetes_1.32.3+ds.orig.tar.gz
14M	upstream-v1.32.3.tar.gz
3.2M	kubernetes_1.32.3+ds.orig.tar.gz

This significant reduction wasn t just about saving space. By removing over 30,000 files, we simplified the package, making it more maintainable. Each dependency could now be properly tracked, updated, and patched independently, resolving the security concerns that had plagued the previous packaging approach.

---

Dependency Graph To give you an idea of the complexity involved in packaging Kubernetes for Debian, the image below is a dependency graph generated with debtree, visualizing all the Go modules and other dependencies required to build the kubectl binary. This web of nodes and edges represents every module and its relationship during the compilation process of kubectl. Each box is a Debian package, and the lines connecting them show how deeply intertwined the ecosystem is. What might look like a mess of blue spaghetti is actually a clear demonstration of the vast and interconnected upstream world that tools like kubectl rely on. But more importantly, this graph is a testament to the effort that went into making kubectl build entirely using Debian-packaged dependencies only, no vendoring, no downloading from the internet, no proprietary blobs.

---

Upstream Version 1.32.3 and Beyond After nearly two years of work, we successfully uploaded version 1.32.3+ds of kubectl to Debian unstable. kubernetes/-/merge_requests/1

• Closed over a dozen long-standing bugs, including:
  • Outdated version requests
  • Missing shell completions
  • VCS (version control system) metadata issues
  • (#1055411, #990793, #1009356, #1016441, #1086756, #1047881, #832706, #976428, #994438)

The new package also includes:

• Zsh, Fish, and Bash completions installed automatically
• Man pages and metadata for improved discoverability
• Full integration with kind and docker for testing purposes

---

Integration Testing with Autopkgtest To ensure the reliability of kubectl in real-world scenarios, we developed a new autopkgtest suite that runs integration tests using real Kubernetes clusters created via Kind. Autopkgtest is a Debian tool used to run automated tests on binary packages. These tests are executed after the package is built but before it s accepted into the Debian archive, helping catch regressions and integration issues early in the packaging pipeline. Our test workflow validates kubectl by performing the following steps:

• Installing Kind and Docker as test dependencies.
• Spinning up two local Kubernetes clusters.
• Switching between cluster contexts to ensure multi-cluster support.
• Deploying and scaling a sample nginx application using kubectl.
• Cleaning up the entire test environment to avoid side effects.
• debian/tests/kubectl.sh

---

Popcon: Measuring Adoption To measure real-world usage, we rely on data from Debian s popularity contest (popcon), which gives insight into how many users have each binary installed. Here s what the data tells us:

• kubectl (new binary): Already installed on 2,124 systems.
• golang-k8s-kubectl-dev: This is the Go development package (a library), useful for other packages and developers who want to interact with Kubernetes programmatically.
• kubernetes-client: The legacy package that kubectl is replacing. We expect this number to decrease in future releases as more systems transition to the new package.

Although the popcon data shows activity for kubectl before the official Debian upload date, it s important to note that those numbers represent users who had it installed from upstream source-lists, not from the Debian repositories. This distinction underscores a demand that existed even before the package was available in Debian proper, and it validates the importance of bringing it into the archive.

Also worth mentioning: this number is not the real total number of installations, since users can choose not to participate in the popularity contest. So the actual adoption is likely higher than what popcon reflects.

---

Community and Documentation The team also maintains a dedicated wiki page which documents:

• Maintained tools and packages
• Contribution guidelines
• Our roadmap for the upcoming Debian releases

https://debian-kubernetes.org

---

Looking Ahead to Debian 13 (Trixie) The next stable release of Debian will ship with kubectl version 1.32.3, built from a clean, de-vendorized source. This version includes nearly all the latest upstream features, and will be the first time in years that Debian users can rely on an up-to-date, policy-compliant kubectl directly from the archive. By comparing with upstream, our Debian package even delivers more out of the box, including shell completions, which the upstream still requires users to generate manually. In 2025, the Debian Kubernetes team will continue expanding our packaging efforts for the Kubernetes ecosystem. Our roadmap includes:

• kubelet: The primary node agent that runs on each node. This will enable Debian users to create fully functional Kubernetes nodes without relying on external packages.
• kubeadm: A tool for creating Kubernetes clusters. With kubeadm in Debian, users will then be able to bootstrap minimum viable clusters directly from the official repositories.
• helm: The package manager for Kubernetes that helps manage applications through Kubernetes YAML files defined as charts.
• kompose: A conversion tool that helps users familiar with docker-compose move to Kubernetes by translating Docker Compose files into Kubernetes resources.

---

Final Thoughts This journey was only possible thanks to the amazing support of the debian-devel-br community and the collective effort of contributors who stepped up to package missing dependencies, fix bugs, and test new versions. Special thanks to:

• Carlos Henrique Melara (@charles)
• Guilherme Puida (@puida)
• Jo o Pedro Nobrega (@jnpf)
• Lucas Kanashiro (@kanashiro)
• Matheus Polkorny (@polkorny)
• Samuel Henrique (@samueloph)
• Sergio Cipriano (@cipriano)
• Sergio Durigan Junior (@sergiodj)

I look forward to continuing this work, bringing more Kubernetes tools into Debian and improving the developer experience for everyone.

A Broken Ecosystem The Kubernetes packaging situation in Debian had been problematic for some time. Given its large codebase and complex dependency tree, the initial packaging approach involved vendorizing all dependencies. While this allowed a somewhat functional package to be published, it introduced several long-term issues, especially security concerns. Vendorized packages bundle third-party dependencies directly into the source tarball. When vulnerabilities arise in those dependencies, it becomes difficult for Debian s security team to patch and rebuild affected packages system-wide. This approach broke Debian s best practices, and it eventually led to the abandonment of the Kubernetes source package, which had stalled at version 1.20.5. Due to this abandonment, critical bugs emerged and the package was removed from Debian s testing channel, as we can see in the package tracker.

---

New Debian Kubernetes Team Around this time, I became a Debian Maintainer (DM), with permissions to upload certain packages. I saw an opportunity to both contribute more deeply to Debian and to fix Kubernetes packaging. In early 2024, just before DebConf Busan in South Korea, I founded the Debian Kubernetes Team. The mission of the team was to repackage Kubernetes in a maintainable, security-conscious, and Debian-compliant way. At DebConf, I shared our progress with the broader community and received great feedback and more visibility, along with people interested in contributing to the team. Our first tasks was to migrate existing Kubernetes-related tools such as kubectx, kubernetes-split-yaml and kubetail into a dedicated namespace on Salsa, Debian s GitLab instance. Many of these tools were stored across different teams (like the Go team), and consolidating them helped us organize development and focus our efforts.

---

De-vendorizing Kubernetes Our main goal was to un-vendorize Kubernetes and bring it up-to-date with upstream releases. This meant:

• Removing the vendor directory and all embedded third-party code.
• Trimming the build scope to focus solely on building kubectl, Kubernetes CLI.
• Using Files-Excluded in debian/copyright to cleanly drop unneeded files during source imports.
• Rebuilding the dependency tree, ensuring all Go modules were separately packaged in Debian.

We used uscan, a standard Debian packaging tool that fetches upstream tarballs and prepares them accordingly. The Files-Excluded directive in our debian/copyright file instructed uscan to automatically remove unnecessary files during the repackaging process:

$ uscan
Newest version of kubernetes on remote site is 1.32.3, specified download version is 1.32.3
Successfully repacked ../v1.32.3 as ../kubernetes_1.32.3+ds.orig.tar.gz, deleting 30616 files from it.

The results were dramatic. By comparing the original upstream tarball with our repackaged version, we can see that our approach reduced the tarball size by over 75%:

$ du -h upstream-v1.32.3.tar.gz kubernetes_1.32.3+ds.orig.tar.gz
14M	upstream-v1.32.3.tar.gz
3.2M	kubernetes_1.32.3+ds.orig.tar.gz

This significant reduction wasn t just about saving space. By removing over 30,000 files, we simplified the package, making it more maintainable. Each dependency could now be properly tracked, updated, and patched independently, resolving the security concerns that had plagued the previous packaging approach.

---

Dependency Graph To give you an idea of the complexity involved in packaging Kubernetes for Debian, the image below is a dependency graph generated with debtree, visualizing all the Go modules and other dependencies required to build the kubectl binary. This web of nodes and edges represents every module and its relationship during the compilation process of kubectl. Each box is a Debian package, and the lines connecting them show how deeply intertwined the ecosystem is. What might look like a mess of blue spaghetti is actually a clear demonstration of the vast and interconnected upstream world that tools like kubectl rely on. But more importantly, this graph is a testament to the effort that went into making kubectl build entirely using Debian-packaged dependencies only, no vendoring, no downloading from the internet, no proprietary blobs.

---

Upstream Version 1.32.3 and Beyond After nearly two years of work, we successfully uploaded version 1.32.3+ds of kubectl to Debian unstable. kubernetes/-/merge_requests/1

• Closed over a dozen long-standing bugs, including:
  • Outdated version requests
  • Missing shell completions
  • VCS (version control system) metadata issues
  • (#1055411, #990793, #1009356, #1016441, #1086756, #1047881, #832706, #976428, #994438)

The new package also includes:

• Zsh, Fish, and Bash completions installed automatically
• Man pages and metadata for improved discoverability
• Full integration with kind and docker for testing purposes

---

Integration Testing with Autopkgtest To ensure the reliability of kubectl in real-world scenarios, we developed a new autopkgtest suite that runs integration tests using real Kubernetes clusters created via Kind. Autopkgtest is a Debian tool used to run automated tests on binary packages. These tests are executed after the package is built but before it s accepted into the Debian archive, helping catch regressions and integration issues early in the packaging pipeline. Our test workflow validates kubectl by performing the following steps:

• Installing Kind and Docker as test dependencies.
• Spinning up two local Kubernetes clusters.
• Switching between cluster contexts to ensure multi-cluster support.
• Deploying and scaling a sample nginx application using kubectl.
• Cleaning up the entire test environment to avoid side effects.
• debian/tests/kubectl.sh

---

Popcon: Measuring Adoption To measure real-world usage, we rely on data from Debian s popularity contest (popcon), which gives insight into how many users have each binary installed. Here s what the data tells us:

• kubectl (new binary): Already installed on 2,124 systems.
• golang-k8s-kubectl-dev: This is the Go development package (a library), useful for other packages and developers who want to interact with Kubernetes programmatically.
• kubernetes-client: The legacy package that kubectl is replacing. We expect this number to decrease in future releases as more systems transition to the new package.

Although the popcon data shows activity for kubectl before the official Debian upload date, it s important to note that those numbers represent users who had it installed from upstream source-lists, not from the Debian repositories. This distinction underscores a demand that existed even before the package was available in Debian proper, and it validates the importance of bringing it into the archive.

Also worth mentioning: this number is not the real total number of installations, since users can choose not to participate in the popularity contest. So the actual adoption is likely higher than what popcon reflects.

---

Community and Documentation The team also maintains a dedicated wiki page which documents:

• Maintained tools and packages
• Contribution guidelines
• Our roadmap for the upcoming Debian releases

https://debian-kubernetes.org

---

Looking Ahead to Debian 13 (Trixie) The next stable release of Debian will ship with kubectl version 1.32.3, built from a clean, de-vendorized source. This version includes nearly all the latest upstream features, and will be the first time in years that Debian users can rely on an up-to-date, policy-compliant kubectl directly from the archive. By comparing with upstream, our Debian package even delivers more out of the box, including shell completions, which the upstream still requires users to generate manually. In 2025, the Debian Kubernetes team will continue expanding our packaging efforts for the Kubernetes ecosystem. Our roadmap includes:

• kubelet: The primary node agent that runs on each node. This will enable Debian users to create fully functional Kubernetes nodes without relying on external packages.
• kubeadm: A tool for creating Kubernetes clusters. With kubeadm in Debian, users will then be able to bootstrap minimum viable clusters directly from the official repositories.
• helm: The package manager for Kubernetes that helps manage applications through Kubernetes YAML files defined as charts.
• kompose: A conversion tool that helps users familiar with docker-compose move to Kubernetes by translating Docker Compose files into Kubernetes resources.

---

Final Thoughts This journey was only possible thanks to the amazing support of the debian-devel-br community and the collective effort of contributors who stepped up to package missing dependencies, fix bugs, and test new versions. Special thanks to:

• Carlos Henrique Melara (@charles)
• Guilherme Puida (@puida)
• Jo o Pedro Nobrega (@jnpf)
• Lucas Kanashiro (@kanashiro)
• Matheus Polkorny (@polkorny)
• Samuel Henrique (@samueloph)
• Sergio Cipriano (@cipriano)
• Sergio Durigan Junior (@sergiodj)

I look forward to continuing this work, bringing more Kubernetes tools into Debian and improving the developer experience for everyone.

• [1] https://www.youtube.com/watch?v=hR9dLdEGn9o
• [2] https://tinyurl.com/249k5cbf
• [3] https://tinyurl.com/2asnzwbz
• [4] https://www.youtube.com/watch?v=es5aPICeXOU
• [5] https://tinyurl.com/27qabt9x
• [6] https://blog.rongarret.info/2010/09/what-would-you-do.html
• [7] https://www.hulver.com/scoop/story/2008/12/14/10333/990
• [8] http://www.aaronsw.com/weblog/epiphany
• [9] https://tinyurl.com/2aobxz4p
• [10] https://www.youtube.com/watch?v=IbaJ97-_dOM
• [11] https://pluralistic.net/2025/01/20/capitalist-unrealism/

Changes in version 0.1.4 (2024-01-29)

• Package maintenance with updates to DESCRIPTION and README.md
• Continunous integration has been update multiple times
• No longer set a C++ compilation standard

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can now sponsor me at GitHub.

1. The closure of the Saint-Michel station had a drastic impact on D'Iberville, the station closest to it.
2. The opening of the Royalmount shopping center nearly doubled the traffic of the De La Savane station.
3. The Montreal subway continues to grow, but has not yet recovered from the pandemic. Berri-UQAM station (the largest one) is still below 1 million entries per quarter compared to its pre-pandemic record.

• Orange line (top10)
• Green line (top10)
• Blue line
• Yellow line
• Global Top 10

• The subway map displayed on this page, the original dataset and my modified dataset are licenced under CCO 1.0: they are in the public domain.
• The R code I wrote is licensed under the GPLv3+. It's pretty much the same code as last year. STM apparently changed (again!) the way they are exporting data, and since it's now somewhat sane, I didn't have to rely on a converter script.

But we, children of a different era, do not want our lives to be enclosed, to be shielded from the mystery. We are eager to participate in it, to gather with our brothers and sisters in a community of thought that will lift us above the mundane. We need to be together in sorrow and in joy. Thus we rarely build monolithic monuments. Instead, we build domes.

With a similar approach, it can be estimated that the chance of an explosion like that at Forty-fifth Street was at most one in thirty million, and probably much less. But this is why life is dangerous and always ends in death.

1. Reproducible Builds mourns the passing of Lunar
2. Introducing reproduce.debian.net
3. New landing page design
4. SBOMs for Python packages
5. Debian updates
6. Reproducible builds by default in Maven 4
7. PyPI now supports digital attestations
8. Dependency Challenges in OSS Package Registries
9. Zig programming language demonstrated reproducible
10. Website updates
11. Upstream patches
12. Misc development news
13. Reproducibility testing framework

Reproducible Builds mourns the passing of Lunar The Reproducible Builds community sadly announced it has lost its founding member, Lunar. J r my Bobbio aka Lunar passed away on Friday November 8th in palliative care in Rennes, France. Lunar was instrumental in starting the Reproducible Builds project in 2013 as a loose initiative within the Debian project. He was the author of our earliest status reports and many of our key tools in use today are based on his design. Lunar s creativity, insight and kindness were often noted. You can view our full tribute elsewhere on our website. He will be greatly missed.

Introducing reproduce.debian.net In happier news, this month saw the introduction of reproduce.debian.net. Announced at the recent Debian MiniDebConf in Toulouse, reproduce.debian.net is an instance of rebuilderd operated by the Reproducible Builds project. rebuilderd is our server designed monitor the official package repositories of Linux distributions and attempts to reproduce the observed results there. In November, reproduce.debian.net began rebuilding Debian unstable on the amd64 architecture, but throughout the MiniDebConf, it had attempted to rebuild 66% of the official archive. From this, it could be determined that it is currently possible to bit-for-bit reproduce and corroborate approximately 78% of the actual binaries distributed by Debian that is, using the .buildinfo files hosted by Debian itself. reproduce.debian.net also contains instructions how to setup one s own rebuilderd instance, and we very much invite everyone with a machine to spare to setup their own version and to share the results. Whilst rebuilderd is still in development, it has been used to reproduce Arch Linux since 2019. We are especially looking for installations targeting Debian architectures other than i386 and amd64.

New landing page design As part of a very productive partnership with the Sovereign Tech Fund and Neighbourhoodie, we are pleased to unveil our new homepage/landing page. We are very happy with our collaboration with both STF and Neighbourhoodie (including many changes not directly related to the website), and look forward to working with them in the future.

SBOMs for Python packages The Python Software Foundation has announced a new cross-functional project for SBOMs and Python packages . Seth Michael Larson writes that the project is specifically looking to solve these issues :

• Enable Python users that require SBOM documents (likely due to regulations like CRA or SSDF) to self-serve using existing SBOM generation tools.
• Solve the phantom dependency problem, where non-Python software is bundled in Python packages but not recorded in any metadata. This makes the job of software composition analysis (SCA) tools difficult or impossible.
• Make the adoption work by relevant projects such as build backends, auditwheel-esque tools, as minimal as possible. Empower users who are interested in having better SBOM data for the Python projects they are using to be able to contribute engineering time towards that goal.

A GitHub repository for the initiative is available, and there are a number of queries, comments and remarks on Seth s Discourse forum post.

Debian updates There was significant development within Debian this month. Firstly, at the recent MiniDebConf in Toulouse, France, Holger Levsen gave a Debian-specific talk on rebuilding packages distributed from ftp.debian.org that is to say, how to reproduce the results from the official Debian build servers: Holger described the talk as follows:

For more than ten years, the Reproducible Builds project has worked towards reproducible builds of many projects, and for ten years now we have build Debian packages twice with maximal variations applied to see if they can be build reproducible still. Since about a month, we ve also been rebuilding trying to exactly match the builds being distributed via ftp.debian.org. This talk will describe the setup and the lessons learned so far, and why the results currently are what they are (spoiler: they are less than 30% reproducible), and what we can do to fix that.

The Debian Project Leader, Andreas Tille, was present at the talk and remarked later in his Bits from the DPL update that:

It might be unfair to single out a specific talk from Toulouse, but I d like to highlight the one on reproducible builds. Beyond its technical focus, the talk also addressed the recent loss of Lunar, whom we mourn deeply. It served as a tribute to Lunar s contributions and legacy. Personally, I ve encountered packages maintained by Lunar and bugs he had filed. I believe that taking over his packages and addressing the bugs he reported is a meaningful way to honor his memory and acknowledge the value of his work.

Holger s slides and video in .webm format are available.
Next, rebuilderd is the server to monitor package repositories of Linux distributions and attempt to reproduce the observed results. This month, version 0.21.0 released, most notably with improved support for binNMUs by Jochen Sprickerhof and updating the rebuilderd-debian.sh integration to the latest debrebuild version by Holger Levsen. There has also been significant work to get the rebuilderd package into the Debian archive, in particular, both rust-rebuilderd-common version 0.20.0-1 and rust-rust-lzma version 0.6.0-1 were packaged by kpcyrd and uploaded by Holger Levsen. Related to this, Holger Levsen submitted three additional issues against rebuilderd as well:

• rebuildctl should be more verbose when encountering issues. [ ]
• Please add an option to used randomised queues. [ ]
• Scheduling and re-scheduling multiple packages at once. [ ]

and lastly, Jochen Sprickerhof submitted one an issue requested that rebuilderd downloads the source package in addition to the .buildinfo file [ ] and kpcyrd also submitted and fixed an issue surrounding dependencies and clarifying the license [ ]
Separate to this, back in 2018, Chris Lamb filed a bug report against the sphinx-gallery package as it generates unreproducible content in various ways. This month, however, Dmitry Shachnev finally closed the bug, listing the multiple sub-issues that were part of the problem and how they were resolved.
Elsewhere, Roland Clobus posted to our mailing list this month, asking for input on a bug in Debian s ca-certificates-java package. The issue is that the Java key management tools embed timestamps in its output, and this output ends up in the /etc/ssl/certs/java/cacerts file on the generated ISO images. A discussion resulted from Roland s post suggesting some short- and medium-term solutions to the problem.
Holger Levsen uploaded some packages with reproducibility-related changes:

• devscripts versions 2.24.3, 2.24.4 and 2.24.5 were uploaded, including several fixes for the debrebuild and debootsnap and scripts.
• cdbs version 0.4.167 uploaded in order to drop dh_buildinfo support, as dpkg has generated .buildinfo files since 2016 and the results of dh_buildinfo are typically unreproducible. Related to this a mass bug filing by Helmut Grohne intended to remove the obsolete and deprecated dh-buildinfo package from the archive. At the time of writing, this still affects 311 packages in Debian unstable.

Lastly, 12 reviews of Debian packages were added, 5 were updated and 21 were removed this month adding to our knowledge about identified issues in Debian.

Reproducible builds by default in Maven 4 On our mailing list this month, Herv Boutemy reported the latest release of Maven (4.0.0-beta-5) has reproducible builds enabled by default. In his mailing list post, Herv mentions that this story started during our Reproducible Builds summit in Hamburg , where he created the upstream issue that builds on a multi-year effort to have Maven builds configured for reproducibility.

PyPI now supports digital attestations Elsewhere in the Python ecosystem and as reported on LWN and elsewhere, the Python Package Index (PyPI) has announced that it has finalised support for PEP 740 ( Index support for digital attestations ). Trail of Bits, who performed much of the development work, has an in-depth blog post about the work and its adoption, as well as what is left undone:

One thing is notably missing from all of this work: downstream verification. [ ] This isn t an acceptable end state (cryptographic attestations have defensive properties only insofar as they re actually verified), so we re looking into ways to bring verification to individual installing clients. In particular, we re currently working on a plugin architecture for pip that will enable users to load verification logic directly into their pip install flows.

There was an in-depth discussion on LWN s announcement page, as well as on Hacker News.

Dependency Challenges in OSS Package Registries At BENEVOL, the Belgium-Netherlands Software Evolution workshop in Namur, Belgium, Tom Mens and Alexandre Decan presented their paper, An Overview and Catalogue of Dependency Challenges in Open Source Software Package Registries . The abstract of their paper is as follows:

While open-source software has enabled significant levels of reuse to speed up software development, it has also given rise to the dreadful dependency hell that all software practitioners face on a regular basis. This article provides a catalogue of dependency-related challenges that come with relying on OSS packages or libraries. The catalogue is based on the scientific literature on empirical research that has been conducted to understand, quantify and overcome these challenges. [ ]

A PDF of the paper is available online.

Zig programming language demonstrated reproducible Motiejus Jak ty posted an interesting and practical blog post on his successful attempt to reproduce the Zig programming language without using the pre-compiled binaries checked into the repository, and despite the circular dependency inherent in its bootstrapping process. As a summary, Motiejus concludes that:

I can now confidently say (and you can also check, you don t need to trust me) that there is nothing hiding in zig1.wasm [the checked-in binary] that hasn t been checked-in as a source file.

The full post is full of practical details, and includes a few open questions.

Website updates Notwithstanding the significant change to the landing page (screenshot above), there were an enormous number of changes made to our website this month. This included:

• Alex Feyerke and Mariano Gim nez:
  • Dramatically overhaul the website s landing page with new benefit cards tailored to the expected visitors to our website and a reworking of the visual hierarchy and design. [ ][ ][ ][ ][ ][ ][ ][ ][ ][ ]
• Bernhard M. Wiedemann:
  • Update the System images page to document the e2fsprogs approach. [ ]
• Chris Lamb:
  • Cachebust every CSS file per-release. [ ]
  • Replace some inline markdown with HTML. [ ]
  • Use spaces on the Publications page. [ ]
  • Add a news article about the passing of Lunar. [ ][ ][ ][ ]
  • Add a black memorial band to the top of the page. [ ]
• FC (Fay) Stegerman:
  • Replace more inline markdown with HTML on the Success stories page. [ ]
  • Add some links, fix some other links and correct some spelling errors on the Tools page. [ ]
• Holger Levsen:
  • Add a historical presentation ( Reproducible builds everywhere eg. in Debian, OpenWrt and LEDE ) from October 2016. [ ]
  • Add jochensp and Oejet to the list of known contributors. [ ][ ]
• Julia Kr ger:
  • Add a new Stripping of unreproducible information page to the documentation. [ ]
• Ninette Adhikari & hulkoba:
  • Add/rework the list of success stories into a new page that clearly shows milestones in Reproducible Builds. [ ][ ][ ][ ][ ][ ]
• Philip Rinn:
  • Import 47 historical weekly reports. [ ]
• hulkoba:
  • Add alt text to almost all images (!). [ ][ ]
  • Fix a number of links on the Talks . [ ][ ]
  • Avoid so-called ghost buttons by not using <button> elements as links, as the affordance of a <button> implies an action with (potentially) a side effect. [ ][ ]
  • Center the sponsor logos on the homepage. [ ]
  • Move publications and generate them instead from a data.yml file with an improved layout. [ ][ ]
  • Make a large number of small but impactful stylisting changes. [ ][ ][ ][ ]
  • Expand the Tools to include a number of missing tools, fix some styling issues and fix a number of stale/broken links. [ ][ ][ ][ ][ ][ ]

Upstream patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:

• Bernhard M. Wiedemann:
  • clisp (fix contributed by Bruno Haible)
  • conky (date-related issue)
  • emacs-auctex (date-related gzip issue)
  • javadoc (filesystem ordering issue)
  • jboss-websocket-1.0-api (embeds uname -r)
  • lcms2 (CPU issue)
  • LiE (ASLR-related issue)
  • make_ext4fs (toolchain-related issue for for VM images)
  • obs-build (issue when running builds with certain CPU types or core numbers)
  • perl-Time-modules (fails to build far in the future)
  • python-bson (fails to build far in the future)
  • python-exiv2 (fails to build far in the future)
  • python-moto (date-related gzip issue)
  • python-pyhanko-certvalidator (fails to build far in the future)
  • python-python-gvm (concurrency-related issue)
  • python310 (fails to build far in the future)
  • python313 (fails to build far in the future)
  • reproducible-faketools (toolchain for emacs)
  • shadowsocks-rust (date-related issue)
  • swipl (fails to build far in the future)
• Chris Lamb:
  • #1087330 filed against python-pydash.
  • #1087485 filed against fritzconnection.
  • #1087486 filed against tracy.
  • #1088238 filed against rust-broot.
  • #1088353 filed against python-aiovlc.
  • #1088742 filed against python-aiohomekit.
• James Addison:
  • #1088144 filed against cdbs.

Misc development news

• Bernhard M. Wiedemann published another report for the openSUSE distribution.
• Martin Abente Lahaye updated diffoscope to fix a crash when objdump is missing. [ ]
• On our mailing list, Jan-Benedict Glaw announced the publication of the fifth NetBSD Reproducibility Report

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework running primarily at tests.reproducible-builds.org in order to check packages and other artifacts for reproducibility. In November, a number of changes were made by Holger Levsen, including:

• reproduce.debian.net-related changes:
  • Create and introduce a new reproduce.debian.net service and subdomain [ ]
  • Make a large number of documentation changes relevant to rebuilderd. [ ][ ][ ][ ][ ]
  • Explain a temporary workaround for a specific issue in rebuilderd. [ ]
  • Setup another rebuilderd instance on the o4 node and update installation documentation to match. [ ][ ]
  • Make a number of helpful/cosmetic changes to the interface, such as clarifying terms and adding links. [ ][ ][ ][ ][ ]
  • Deploy configuration to the /opt and /var directories. [ ][ ]
  • Add an infancy (or alpha ) disclaimer. [ ][ ]
  • Add more notes to the temporary rebuilderd documentation. [ ]
  • Commit an nginx configuration file for reproduce.debian.net s Stats page. [ ]
  • Commit a rebuilder-worker.conf configuration for the o5 node. [ ]
• Debian-related changes:
  • Grant jspricke and jochensp access to the o5 node. [ ][ ]
  • Build the qemu package with the nocheck build flag. [ ]
• Misc changes:
  • Adapt the update_jdn.sh script for new Debian trixie systems. [ ]
  • Stop installing the PostgreSQL database engine on the o4 and o5 nodes. [ ]
  • Prevent accidental reboots of the o4 node because of a long-running job owned by josch. [ ][ ]

In addition, Mattia Rizzolo addressed a number of issues with reproduce.debian.net [ ][ ][ ][ ]. And lastly, both Holger Levsen [ ][ ][ ][ ] and Vagrant Cascadian [ ][ ][ ][ ] performed node maintenance.
If you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

• IRC: #reproducible-builds on irc.oftc.net.
• Mastodon: @reproducible_builds@fosstodon.org
• Mailing list: rb-general@lists.reproducible-builds.org
• Twitter: @ReproBuilds

The last of the five was the only one who did not share a certain martial quality. He was slim and well-groomed and would be considered handsome, but he was also extraordinarily pale, as if he lived his life underground. It was this fifth man who nudged the corpse with the toe of his boot and said, "Well, if you want my professional opinion, this great goddamn hole in his chest is probably what killed him."

"God's stripes." Earstripe shook his head in disbelief. "Bone-doctor would save some gnole, yes? If some gnole was hurt." "Of course," said Piper. "If I could." "And tomato-man would save some gnole?" He swung his muzzle toward Galen. "If some gnome needed big human with sword?" "Yes, of course." Earstripe spread his hands, claws gleaming. "A gnole saves some human. Same thing." He took a deep breath, clearly choosing his words carefully. "A gnole's compassion does not require fur."

1. Catch the lightning talk summarizing the meeting here (you can even speed up 2x):

1. For a quick written summary, scroll down to the TL;DR section.

TL;DR This meeting took 3 hours and tackled a variety of topics related to DRM/KMS (Linux/DRM Kernel Modesetting):

• Sharing Drivers Between V4L2 and KMS: Brainstorming solutions for using a single driver for devices used in both camera capture and display pipelines.
• Real-Time Scheduling: Addressing issues with non-blocking page flips encountering sigkills under real-time scheduling.
• HDR/Color Management: Agreement on merging the current proposal, with NVIDIA implementing its special cases on VKMS and adding missing parts on top of Harry Wentland s (AMD) changes.
• Display Mux: Collaborative design discussions focusing on compositor control and cross-sync considerations.
• Better Commit Failure Feedback: Exploring ways to equip compositors with more detailed information for failure analysis.

---

Bringing together Linux display developers in the XDC 2024 While I didn t present a talk this year, I co-organized a Display/KMS meeting (with Rodrigo Siqueira of AMD) to build upon the momentum from the 2024 Linux Display Next hackfest. The meeting was attended by around 30 people in person and 4 remote participants. Speakers: Melissa Wen (Igalia) and Rodrigo Siqueira (AMD) Link: https://indico.freedesktop.org/event/6/contributions/383/ Topics: Similar to the hackfest, the meeting agenda was built over the first two days of the conference and mixed talks follow-up with new ideas and ongoing community efforts. The final agenda covered five topics in the scheduled order:

1. How to share drivers between V4L2 and DRM for bridge-like components (new topic);
2. Real-time Scheduling (problems encountered after the Display Next hackfest);
3. HDR/Color Management (ofc);
4. Display Mux (from Display hackfest and XDC 2024 talk, bringing AMD and NVIDIA together);
5. (Better) Commit Failure Feedback (continuing the last minute topic of the Display Next hackfest).

Unpacking the Topics Similar to the hackfest, the meeting agenda evolved over the conference. During the 3 hours of meeting, I coordinated the room and discussion rounds, and Rodrigo Siqueira took notes and also contacted key developers to provide a detailed report of the many topics discussed. From his notes, let s dive into the key discussions!

How to share drivers between V4L2 and KMS for bridge-like components. Led by Laurent Pinchart, we delved into the challenge of creating a unified driver for hardware devices (like scalers) that are used in both camera capture pipelines and display pipelines.

• Problem Statement: How can we design a single kernel driver to handle devices that serve dual purposes in both V4L2 and DRM subsystems?
• Potential Solutions:
  1. Multiple Compatible Strings: We could assign different compatible strings to the device tree node based on its usage in either the camera or display pipeline. However, this approach might raise concerns from device tree maintainers as it could be seen as a layer violation.
  2. Separate Abstractions: A single driver could expose the device to both DRM and V4L2 through separate abstractions: drm-bridge for DRM and V4L2 subdev for video. While simple, this approach requires maintaining two different abstractions for the same underlying device.
  3. Unified Kernel Abstraction: We could create a new, unified kernel abstraction that combines the best aspects of drm-bridge and V4L2 subdev. This approach offers a more elegant solution but requires significant design effort and potential migration challenges for existing hardware.

Real-Time Scheduling Challenges We have discussed real-time scheduling during this year Linux Display Next hackfest and, during the XDC 2024, Jonas Adahl brought up issues uncovered while progressing on this front.

• Context: Non-blocking page-flips can, on rare occasions, take a long time and, for that reason, get a sigkill if the thread doing the atomic commit is a real-time schedule.
• Action items:
  • Explore alternative backtraces during the busy wait (e.g., ftrace).
  • Investigate the maximum thread time in busy wait to reproduce issues faced by compositors. Tools like RTKit (mutter) can be used for better control (Michel D nzer can help with this setup).

HDR/Color Management This is a well-known topic with ongoing effort on all layers of the Linux Display stack and has been discussed online and in-person in conferences and meetings over the last years. Here s a breakdown of the key points raised at this meeting:

• Talk: Color operations for Linux color pipeline on AMD devices: In the previous day, Alex Hung (AMD) presented the implementation of this API on AMD display driver.
• NVIDIA Integration: While they agree with the overall proposal, NVIDIA needs to add some missing parts. Importantly, they will implement these on top of Harry Wentland s (AMD) proposal. Their specific requirements will be implemented on VKMS (Virtual Kernel Mode Setting driver) for further discussion. This VKMS implementation can benefit compositor developers by providing insights into NVIDIA s specific needs.
• Other vendors: There is a version of the KMS API applied on Intel color pipeline. Apart from that, other vendors appear to be comfortable with the current proposal but lacks the bandwidth to implement it right now.
• Upstream Patches: The relevant upstream patches were can be found here. [As humorously notes, this series is eagerly awaiting your Acked-by (approval)]
• Compositor Side: The compositor developers have also made significant progress.
  • KDE has already implemented and validated the API through an experimental implementation in Kwin.
  • Gamescope currently uses a driver-specific implementation but has a draft that utilizes the generic version. However, some work is still required to fully transition away from the driver-specific approach. AP: work on porting gamescope to KMS generic API
  • Weston has also begun exploring implementation, and we might see something from them by the end of the year.
• Kernel and Testing: The kernel API proposal is well-refined and meets the DRM subsystem requirements. Thanks to Harry Wentland effort, we already have the API attached to two hardware vendors and IGT tests, and, thanks to Xaver Hugl, a compositor implementation in place.

Finally, there was a strong sense of agreement that the current proposal for HDR/Color Management is ready to be merged. In simpler terms, everything seems to be working well on the technical side - all signs point to merging and shipping the DRM/KMS plane color management API!

Display Mux During the meeting, Daniel Dadap led a brainstorming session on the design of the display mux switching sequence, in which the compositor would arm the switch via sysfs, then send a modeset to the outgoing driver, followed by a modeset to the incoming driver.

• Context:
  • During this year Linux Display Next hackfest, Mario Limonciello (AMD) introduced the topic and led a discussion on Display Mux.
  • Daniel Dadap (NVIDIA) retook this discussion with the XDC 2024 talk: Dynamic Switching of Display Muxes on Hybrid GPU Systems.
• Key Considerations:
  • HPD Handling: There was a general consensus that disabling HPD can be part of the sequence for internal panels and we don t need to focus on it here.
  • Cross-Sync: Ensuring synchronization between the compositor and the drivers is crucial. The compositor should act as the drm-master to coordinate the entire sequence, but how can this be ensured?
  • Future-Proofing: The design should not assume the presence of a mux. In future scenarios, direct sharing over DP might be possible.
• Action points:
  • Sharing DP AUX: Explore the idea of sharing DP AUX and its implications.
  • Backlight: The backlight definition represents a problem in the mux switch context, so we should explore some of the current specs available for that.

Towards Better Commit Failure Feedback In the last part of the meeting, Xaver Hugl asked for better commit failure feedback.

• Problem description: Compositors currently face challenges in collecting detailed information from the kernel about commit failures. This lack of granular data hinders their ability to understand and address the root causes of these failures.

To address this issue, we discussed several potential improvements:

• Direct Kernel Log Access: One idea is to directly load relevant kernel logs into the compositor. This would provide more detailed information about the failure and potentially aid in debugging.
• Finer-Grained Failure Reporting: We also explored the possibility of separating atomic failures into more specific categories. Not all failures are critical, and understanding the nature of the failure can help compositors take appropriate action.
• Enhanced Logging: Currently, the dmesg log doesn t provide enough information for user-space validation. Raising the log level to capture more detailed information during failures could be a viable solution.

By implementing these improvements, we aim to equip compositors with the necessary tools to better understand and resolve commit failures, leading to a more robust and stable display system.

A Big Thank You! Huge thanks to Rodrigo Siqueira for these detailed meeting notes. Also, Laurent Pinchart, Jonas Adahl, Daniel Dadap, Xaver Hugl, and Harry Wentland for bringing up interesting topics and leading discussions. Finally, thanks to all the participants who enriched the discussions with their experience, ideas, and inputs, especially Alex Goins, Antonino Maniscalco, Austin Shafer, Daniel Stone, Demi Obenour, Jessica Zhang, Joan Torres, Leo Li, Liviu Dudau, Mario Limonciello, Michel D nzer, Rob Clark, Simon Ser and Teddy Li. This collaborative effort will undoubtedly contribute to the continued development of the Linux display stack. Stay tuned for future updates!

• [1] https://blog.jeujeus.de/blog/hardware/laptops-will-not-sleep-anymore/
• [2] https://tinyurl.com/2b7mxaj7
• [3] https://www.youtube.com/watch?v=OHKKcd3sx2c

The coffee shop Ibtehal and me used to visit during the midnight

Grating at a chemist shop in Mombasa, Kenya

A visit to Nairobi s Historic Cricket Ground On this trip, I got a unique souvenir that can t be purchased from the market a cricket jersey worn in an ODI match by a player. The story goes as follows: I was roaming around the market with my friend Benson from Nairobi to buy a Kenyan cricket jersey for myself, but we couldn t find any. So, Benson had the idea of visiting the Nairobi Gymkhana Club, which used to be Kenya s main cricket ground. It has hosted some historic matches, including the 2003 World Cup match in which Kenya beat the mighty Sri Lankans and the record for the fastest ODI century by Shahid Afridi in just 37 balls in 1996. Although entry to the club was exclusively for members, I was warmly welcomed by the staff. Upon reaching the cricket ground, I met some Indian players who played in Kenyan leagues, as well as Lucas Oluoch and Dominic Wesonga, who have represented Kenya in ODIs. When I expressed interest in getting a jersey, Dominic agreed to send me pictures of his jersey. I liked his jersey and collected it from him. I gave him 2000 shillings, an amount suggested by those Indian players.

Me with players at the Nairobi Gymkhana Club

Cricket pitch at the Nairobi Gymkhana Club

A view of the cricket ground inside the Nairobi Gymkhana Club

Scoreboard at the Nairobi Gymkhana cricket ground

Giraffe Center in Nairobi Kenya is known for its safaris and has no shortage of national parks. In fact, Nairobi is the only capital in the world with a national park. I decided not to visit one, as most of them were expensive and offered multi-day tours, and I didn t want to spend that much time in the wildlife. Instead, I went to the Giraffe Center in Nairobi with Pragya and Rabina. The ticket cost 1500 Kenyan shillings (1000 Indian rupees). In Kenya, matatus - shared vans, usually decorated with portraits of famous people and play rap songs - are the most popular means of public transport. Reaching the Giraffe Center from our hotel required taking five matatus, which cost a total of 150 shillings, and a 2 km walk. The journey back was 90 shillings, suggesting that we didn t find the most efficient route to get there. At the Giraffe Center, we fed giraffes and took photos.

A matatu with a Notorious BIG portrait.

Inside the Giraffe Center

Train ride from Nairobi to Mombasa I took a train from Nairobi to Mombasa. The train is known as the SGR Train, where SGR refers to Standard Gauge Railway. The journey was around 500 km. M-Pesa was the only way to make payment for pre-booking the train ticket, and I didn t have an M-Pesa account. Pragya s friend Mary helped facilitate the payment. I booked a second-class ticket, which cost 1500 shillings (1000 Indian rupees). The train was scheduled to depart from Nairobi at 08:00 hours in the morning and arrive in Mombasa at 14:00 hours. The security check at the station required scanning our bags and having them sniffed by sniffer dogs. I also fell victim to a scam by a security official who offered to help me get my ticket printed, only to later ask me to get him some coffee, which I politely declined. Before boarding the train, I was treated to some stunning views at the Nairobi Terminus station. It was a seating train, but I wished it were a sleeper train, as I was sleep-deprived. The train was neat and clean, with good toilets. The train reached Mombasa on time at around 14:00 hours.

SGR train at Nairobi Terminus.

Interior of the SGR train

Arrival in Mombasa

Mombasa Terminus station.

Mombasa was a bit hotter than Nairobi, with temperatures reaching around 30 degrees Celsius. However, that s not too hot for me, as I am used to higher temperatures in India. I had booked a hostel in the Old Town and was searching for a hitchhike from the Mombasa Terminus station. After trying for more than half an hour, I took a matatu that dropped me 3 km from my hostel for 200 shillings (140 Indian rupees). I tried to hitchhike again but couldn t find a ride. I think I know why I couldn t get a ride in both the cases. In the first case, the Mombasa Terminus was in an isolated place, so most of the vehicles were taxis or matatus while any noncommercial cars were there to pick up friends and family. If the station were in the middle of the city, there would be many more car/truck drivers passing by, thus increasing my possibilities of getting a ride. In the second case, my hostel was at the end of the city, and nobody was going towards that side. In fact, many drivers told me they would love to give me a ride, but they were going in some other direction. Finally, I took a tuktuk for 70 shillings to reach my hostel, Tulia Backpackers. It was 11 USD (1400 shillings) for one night. The balcony gave a nice view of the Indian Ocean. The rooms had fans, but there was no air conditioning. Each bed also had mosquito nets. The place was walking distance of the famous Fort Jesus. Mombasa has had more Islamic influence compared to Nairobi and also has many Hindu temples.

The balcony at Tulia Backpackers Hostel had a nice view of the ocean.

A room inside the hostel with fans and mosquito nets on the beds

Visiting White Sandy Beaches and Getting a Hitchhike Visiting Nyali beach marked my first time ever at a white sand beach. It was like 10 km from the hostel. The next day, I visited Diani Beach, which was 30 km from the hostel. Going to Diani Beach required crossing a river, for which there s a free ferry service every few minutes, followed by taking a matatu to Ukunda and then a tuk-tuk. The journey gave me a glimpse of the beautiful countryside of Kenya.

Nyali beach is a white sand beach

This is the ferry service for crossing the river.

During my return from Diani Beach to the hostel, I was successful in hitchhiking. However, it was only a 4 km ride and not sufficient to reach Ukunda, so I tried to get another ride. When a truck stopped for me, I asked for a ride to Ukunda. Later, I learned that they were going in the same direction as me, so I got off within walking distance from my hostel. The ride was around 30 km. I also learned the difference between a truck ride and a matatu or car ride. For instance, matatus and cars are much faster and cooler due to air conditioning, while trucks tend to be warmer because they lack it. Further, the truck was stopped at many checkpoints by the police for inspections as it carried goods, which is not the case with matatus. Anyways, it was a nice experience, and I am grateful for the ride. I had a nice conversation with the truck drivers about Indian movies and my experiences in Kenya.

Diani beach is a popular beach in Kenya. It is a white sand beach.

Selfie with truck drivers who gave me the free ride

Back to Nairobi I took the SGR train from Mombasa back to Nairobi. This time I took the night train, which departs at 22:00 hours, reaching Nairobi at around 04:00 in the morning. I could not sleep comfortably since the train only had seater seats. I had booked the Zarita Hotel in Nairobi and had already confirmed if they allowed early morning check-in. Usually, hotels have a fixed checkout time, say 11:00 in the morning, and you are not allowed to stay beyond that regardless of the time you checked in. But this hotel checked me in for 24 hours. Here, I paid in US dollars, and the cost was 12 USD.

Almost Got Stuck in Kenya Two days before my scheduled flight from Nairobi back to India, I heard the news that the airports in Kenya were closed due to the strikes. Rabina and Pragya had their flight back to Nepal canceled that day, which left them stuck in Nairobi for two additional days. I called Sahil in India and found out during the conversation that the strike was called off in the evening. It was a big relief for me, and I was fortunate to be able to fly back to India without any changes to my plans.

Newspapers at a stand in Kenya covering news on the airport closure

Experience with locals I had no problems communicating with Kenyans, as everyone I met knew English to an extent that could easily surpass that of big cities in India. Additionally, I learned a few words from Kenya s most popular local language, Swahili, such as Asante, meaning thank you, Jambo for hello, and Karibu for welcome. Knowing a few words in the local language went a long way. I am not sure what s up with haggling in Kenya. It wasn t easy to bring the price of souvenirs down. I bought a fridge magnet for 200 shillings, which was the quoted price. On the other hand, it was much easier to bargain with taxis/tuktuks/motorbikes. I stayed at three hotels/hostels in Kenya. None of them had air conditioners. Two of the places were in Nairobi, and they didn t even have fans in the rooms, while the one in Mombasa had only fans. All of them had good Wi-Fi, except Tulia where the internet overall was a bit shaky. My experience with the hotel staff was great. For instance, we requested that the Nairobi Transit Hotel cancel the included breakfast in order to reduce the room costs, but later realized that it was not a good idea. The hotel allowed us to revert and even offered one of our missing breakfasts during dinner. The staff at Tulia Backpackers in Mombasa facilitated the ticket payment for my train from Mombasa to Nairobi. One of the staff members also gave me a lift to the place where I could catch a matatu to Nyali Beach. They even added an extra tea bag to my tea when I requested it to be stronger.

Food At the Nairobi Transit Hotel, a Spanish omelet with tea was served for breakfast. I noticed that Spanish omelette appeared on the menus of many restaurants, suggesting that it is popular in Kenya. This was my first time having this dish. The milk tea in Kenya, referred to by locals as white tea, is lighter than Indian tea (they don t put a lot of tea leaves).

Spanish Omelette served in breakfast at Nairobi Transit Hotel

I also sampled ugali with eggs. In Mombasa, I visited an Indian restaurant called New Chetna and had a buffet thali there twice.

Ugali with eggs.

Tips for Exchanging Money In Kenya, I exchanged my money at forex shops a couple of times. I received good exchange rates for bills larger than 50 USD. For instance, 1 USD on xe.com was 129 shillings, and I got 128.3 shillings per USD (a total of 12,830 shillings) for two 50 USD notes at an exchange in Nairobi, while 127 shillings, which was the highest rate at the banks. On the other hand, for smaller bills such as a one US dollar note, I would have got 125 shillings. A passport was the only document required for the exchange, and they also provided a receipt. A good piece of advice for travelers is to keep 50 USD or larger bills for exchanging into the local currency while saving the smaller US dollar bills for accommodation, as many hotels and hostels accept payment in US dollars (in addition to Kenyan shillings).

Missed Malindi and Lamu There were more places on my to-visit list in Kenya. But I simply didn t have time to cover them, as I don t like rushing through places, especially in a foreign country where there is a chance of me underestimating the amount of time it takes during transit. I would have liked to visit at least one of Kilifi, Watamu or Malindi beaches. Further, Lamu seemed like a unique place to visit as it has no cars or motorized transport; the only options for transport are boats and donkeys. That s it for now. Meet you in the next one :)

A dpkg trigger is a facility that allows events caused by one package but of interest to another package to be recorded and aggregated, and processed later by the interested package. This feature simplifies various registration and system-update tasks and reduces duplication of processing.

#!/bin/bash
set -e
echo "Signing the new systemd-bootx64.efi"
sbsign --key /etc/secureboot/db.key --cert /etc/secureboot/db.crt \
       /usr/lib/systemd/boot/efi/systemd-bootx64.efi
echo "Invoking bootctl install to copy stuff"
bootctl install

# trigger 1 interest on systemd-bootx64.efi
interest-noawait /usr/lib/systemd/boot/efi/systemd-bootx64.efi

sudo apt install --reinstall systemd-boot-efi

Sep 29 13:42:51 chamunda systemd[1]: Stopping systemd-boot-update.service - Automatic Boot Loader Update...
Sep 29 13:42:51 chamunda systemd[1]: Starting systemd-boot-update.service - Automatic Boot Loader Update...
Sep 29 13:42:51 chamunda bootctl[1801516]: Skipping "/efi/EFI/systemd/systemd-bootx64.efi", same boot loader version in place already.
Sep 29 13:42:51 chamunda bootctl[1801516]: Skipping "/efi/EFI/BOOT/BOOTX64.EFI", same boot loader version in place already.
Sep 29 13:42:51 chamunda bootctl[1801516]: Skipping "/efi/EFI/BOOT/BOOTX64.EFI", same boot loader version in place already.
Sep 29 13:42:51 chamunda systemd[1]: Finished systemd-boot-update.service - Automatic Boot Loader Update.
Sep 29 13:43:37 chamunda systemd[1]: systemd-boot-update.service: Deactivated successfully.
Sep 29 13:43:37 chamunda systemd[1]: Stopped systemd-boot-update.service - Automatic Boot Loader Update.
Sep 29 13:43:37 chamunda systemd[1]: Stopping systemd-boot-update.service - Automatic Boot Loader Update...

Organization Highlights The hackfest was marked by in-depth discussions and knowledge sharing among Linux contributors, making everyone inspired, informed, and connected to the community. Building on feedback from the previous year, we refined the unconference format to enhance participant preparation and engagement. Structured Agenda and Timeboxes: Each session had a defined scope, time limit (1h20 or 2h10), and began with an introductory talk on the topic.

• Participant-Led Discussions: We pre-selected in-person participants to lead discussions, allowing them to prepare introductions, resources, and scope.
• Transparent Scheduling: The schedule was shared in advance as GitHub issues, encouraging participants to review and prepare for sessions of interest.

Engaging Sessions: The hackfest featured a variety of topics, including presentations and discussions on how participants were addressing specific subjects within their companies.

• No Breakout Rooms, No Overlaps: All participants chose to attend all sessions, eliminating the need for separate breakout rooms. We also adapted run-time schedule to keep everybody involved in the same topics.
• Real-time Updates: We provided notifications and updates through dedicated emails and the event matrix room.

Strengthening Community Connections: The hackfest offered ample opportunities for networking among attendees.

• Social Events: Igalia sponsored coffee breaks, lunches, and a dinner at a local restaurant.
• Museum Visit: Participants enjoyed a sponsored visit to the Museum of Estrela Galicia Beer (MEGA).

Fruitful Discussions and Follow-up The structured agenda and breaks allowed us to cover multiple topics during the hackfest. These discussions have led to new display feature development and improvements, as evidenced by patches, merge requests, and implementations in project repositories and mailing lists. With the KMS color management API taking shape, we discussed refinements and best approaches to cover the variety of color pipeline from different hardware-vendors. We are also investigating techniques for a performant SDR<->HDR content reproduction and reducing latency and power consumption when using the color blocks of the hardware.

Color Management/HDR Color Management and HDR continued to be the hottest topic of the hackfest. We had three sessions dedicated to discuss Color and HDR across Linux Display stack layers.

Color/HDR (Kernel-Level) Harry Wentland (AMD) led this session. Here, kernel Developers shared the Color Management pipeline of AMD, Intel and NVidia. We counted with diagrams and explanations from HW-vendors developers that discussed differences, constraints and paths to fit them into the KMS generic color management properties such as advertising modeset needs, IN\_FORMAT, segmented LUTs, interpolation types, etc. Developers from Qualcomm and ARM also added information regarding their hardware. Upstream work related to this session:

• KMS color management properties (new version - v5);
• IGT Tests;
• drm_info draft support of v4 DRM/KMS plane color properties;
• gamescope draft support of v4 DRM/KMS plane color properties;
• Kwin WIP implementation of DRM/KMS plane color properties.

Color/HDR (Compositor-Level) Sebastian Wick (RedHat) led this session. It started with Sebastian s presentation covering Wayland color protocols and compositor implementation. Also, an explanation of APIs provided by Wayland and how they can be used to achieve better color management for applications and discussions around ICC profiles and color representation metadata. There was also an intensive Q&A about LittleCMS with Marti Maria. Upstream work related to this session:

• Wayland color management protocol;
• Wayland color representation protocol;
• HDR support merged on Mutter;
• Color management protocol on Mutter;
• Color management protocol on GTK.

Color/HDR (Use Cases and Testing) Christopher Cameron (Google) and Melissa Wen (Igalia) led this session. In contrast to the other sessions, here we focused less on implementation and more on brainstorming and reflections of real-world SDR and HDR transformations (use and validation) and gainmaps. Christopher gave a nice presentation explaining HDR gainmap images and how we should think of HDR. This presentation and Q&A were important to put participants at the same page of how to transition between SDR and HDR and somehow emulating HDR. We also discussed on the usage of a kernel background color property. Finally, we discussed a bit about Chamelium and the future of VKMS (future work and maintainership).

Power Savings vs Color/Latency Mario Limonciello (AMD) led this session. Mario gave an introductory presentation about AMD ABM (adaptive backlight management) that is similar to Intel DPST. After some discussions, we agreed on exposing a kernel property for power saving policy. This work was already merged on kernel and the userspace support is under development. Upstream work related to this session:

• Kernel series: Add support for power saving policy property (merged)
• Mutter: issue: support for power saving policy property
• Kwin: MR Draft: backends/drm: add support for the power saving policy property

Strategy for video and gaming use-cases Leo Li (AMD) led this session. Miguel Casas (Google) started this session with a presentation of Overlays in Chrome/OS Video, explaining the main goal of power saving by switching off GPU for accelerated compositing and the challenges of different colorspace/HDR for video on Linux. Then Leo Li presented different strategies for video and gaming and we discussed the userspace need of more detailed feedback mechanisms to understand failures when offloading. Also, creating a debugFS interface came up as a tool for debugging and analysis.

Real-time scheduling and async KMS API Xaver Hugl (KDE/BlueSystems) led this session. Compositor developers have exposed some issues with doing real-time scheduling and async page flips. One is that the Kernel limits the lifetime of realtime threads and if a modeset takes too long, the thread will be killed and thus the compositor as well. Also, simple page flips take longer than expected and drivers should optimize them. Another issue is the lack of feedback to compositors about hardware programming time and commit deadlines (the lastest possible time to commit). This is difficult to predict from drivers, since it varies greatly with the type of properties. For example, color management updates take much longer. In this regard, we discusssed implementing a hw_done callback to timestamp when the hardware programming of the last atomic commit is complete. Also an API to pre-program color pipeline in a kind of A/B scheme. It may not be supported by all drivers, but might be useful in different ways.

VRR/Frame Limit, Display Mux, Display Control, and more and beer We also had sessions to discuss a new KMS API to mitigate headaches on VRR and Frame Limit as different brightness level at different refresh rates, abrupt changes of refresh rates, low frame rate compensation (LFC) and precise timing in VRR more. On Display Control we discussed features missing in the current KMS interface for HDR mode, atomic backlight settings, source-based tone mapping, etc. We also discussed the need of a place where compositor developers can post TODOs to be developed by KMS people. The Content-adaptive Scaling and Sharpening session focused on sharpening and scaling filters. In the Display Mux session, we discussed proposals to expose the capability of dynamic mux switching display signal between discrete and integrated GPUs. In the last session of the 2024 Display Next Hackfest, participants representing different compositors summarized current and future work and built a Linux Display wish list , which includes: improvements to VTTY and HDR switching, better dmabuf API for multi-GPU support, definition of tone mapping, blending and scaling sematics, and wayland protocols for advertising to clients which colorspaces are supported. We closed this session with a status update on feature development by compositors, including but not limited to: plane offloading (from libcamera to output) / HDR video offloading (dma-heaps) / plane-based scrolling for web pages, color management / HDR / ICC profiles support, addressing issues such as flickering when color primaries don t match, etc. After three days of intensive discussions, all in-person participants went to a guided tour at the Museum of Extrela Galicia beer (MEGA), pouring and tasting the most famous local beer.

Feedback and Future Directions Participants provided valuable feedback on the hackfest, including suggestions for future improvements.

• Schedule and Break-time Setup: Having a pre-defined agenda and schedule provided a better balance between long discussions and mental refreshments, preventing the fatigue caused by endless discussions.
• Action Points: Some participants recommended explicitly asking for action points at the end of each session and assigning people to follow-up tasks.
• Remote Participation: Remote attendees appreciated the inclusive setup and opportunities to actively participate in discussions.
• Technical Challenges: There were bandwidth and video streaming issues during some sessions due to the large number of participants.

Thank you for joining the 2024 Display Next Hackfest We can t help but thank the 40 participants, who engaged in-person or virtually on relevant discussions, for a collaborative evolution of the Linux display stack and for building an insightful agenda. A big thank you to the leaders and presenters of the nine sessions: Christopher Cameron (Google), Harry Wentland (AMD), Leo Li (AMD), Mario Limoncello (AMD), Sebastian Wick (RedHat) and Xaver Hugl (KDE/BlueSystems) for the effort in preparing the sessions, explaining the topic and guiding discussions. My acknowledge to the others in-person participants that made such an effort to travel to A Coru a: Alex Goins (NVIDIA), David Turner (Raspberry Pi), Georges Stavracas (Igalia), Joan Torres (SUSE), Liviu Dudau (Arm), Louis Chauvet (Bootlin), Robert Mader (Collabora), Tian Mengge (GravityXR), Victor Jaquez (Igalia) and Victoria Brekenfeld (System76). It was and awesome opportunity to meet you and chat face-to-face. Finally, thanks virtual participants who couldn t make it in person but organized their days to actively participate in each discussion, adding different perspectives and valuable inputs even remotely: Abhinav Kumar (Qualcomm), Chaitanya Borah (Intel), Christopher Braga (Qualcomm), Dor Askayo (Red Hat), Jiri Koten (RedHat), Jonas dahl (Red Hat), Leandro Ribeiro (Collabora), Marti Maria (Little CMS), Marijn Suijten, Mario Kleiner, Martin Stransky (Red Hat), Michel D nzer (Red Hat), Miguel Casas-Sanchez (Google), Mitulkumar Golani (Intel), Naveen Kumar (Intel), Niels De Graef (Red Hat), Pekka Paalanen (Collabora), Pichika Uday Kiran (AMD), Shashank Sharma (AMD), Sriharsha PV (AMD), Simon Ser, Uma Shankar (Intel) and Vikas Korjani (AMD). We look forward to another successful Display Next hackfest, continuing to drive innovation and improvement in the Linux display ecosystem!

Organization Highlights The hackfest was marked by in-depth discussions and knowledge sharing among Linux contributors, making everyone inspired, informed, and connected to the community. Building on feedback from the previous year, we refined the unconference format to enhance participant preparation and engagement. Structured Agenda and Timeboxes: Each session had a defined scope, time limit (1h20 or 2h10), and began with an introductory talk on the topic.

• Participant-Led Discussions: We pre-selected in-person participants to lead discussions, allowing them to prepare introductions, resources, and scope.
• Transparent Scheduling: The schedule was shared in advance as GitHub issues, encouraging participants to review and prepare for sessions of interest.

Engaging Sessions: The hackfest featured a variety of topics, including presentations and discussions on how participants were addressing specific subjects within their companies.

• No Breakout Rooms, No Overlaps: All participants chose to attend all sessions, eliminating the need for separate breakout rooms. We also adapted run-time schedule to keep everybody involved in the same topics.
• Real-time Updates: We provided notifications and updates through dedicated emails and the event matrix room.

Strengthening Community Connections: The hackfest offered ample opportunities for networking among attendees.

• Social Events: Igalia sponsored coffee breaks, lunches, and a dinner at a local restaurant.
• Museum Visit: Participants enjoyed a sponsored visit to the Museum of Estrela Galicia Beer (MEGA).

Fruitful Discussions and Follow-up The structured agenda and breaks allowed us to cover multiple topics during the hackfest. These discussions have led to new display feature development and improvements, as evidenced by patches, merge requests, and implementations in project repositories and mailing lists. With the KMS color management API taking shape, we discussed refinements and best approaches to cover the variety of color pipeline from different hardware-vendors. We are also investigating techniques for a performant SDR<->HDR content reproduction and reducing latency and power consumption when using the color blocks of the hardware.

Color Management/HDR Color Management and HDR continued to be the hottest topic of the hackfest. We had three sessions dedicated to discuss Color and HDR across Linux Display stack layers.

Color/HDR (Kernel-Level) Harry Wentland (AMD) led this session. Here, kernel Developers shared the Color Management pipeline of AMD, Intel and NVidia. We counted with diagrams and explanations from HW-vendors developers that discussed differences, constraints and paths to fit them into the KMS generic color management properties such as advertising modeset needs, IN\_FORMAT, segmented LUTs, interpolation types, etc. Developers from Qualcomm and ARM also added information regarding their hardware. Upstream work related to this session:

• KMS color management properties (new version - v5);
• IGT Tests;
• drm_info draft support of v4 DRM/KMS plane color properties;
• gamescope draft support of v4 DRM/KMS plane color properties;
• Kwin WIP implementation of DRM/KMS plane color properties.

Color/HDR (Compositor-Level) Sebastian Wick (RedHat) led this session. It started with Sebastian s presentation covering Wayland color protocols and compositor implementation. Also, an explanation of APIs provided by Wayland and how they can be used to achieve better color management for applications and discussions around ICC profiles and color representation metadata. There was also an intensive Q&A about LittleCMS with Marti Maria. Upstream work related to this session:

• Wayland color management protocol;
• Wayland color representation protocol;
• HDR support merged on Mutter;
• Color management protocol on Mutter;
• Color management protocol on GTK.

Color/HDR (Use Cases and Testing) Christopher Cameron (Google) and Melissa Wen (Igalia) led this session. In contrast to the other sessions, here we focused less on implementation and more on brainstorming and reflections of real-world SDR and HDR transformations (use and validation) and gainmaps. Christopher gave a nice presentation explaining HDR gainmap images and how we should think of HDR. This presentation and Q&A were important to put participants at the same page of how to transition between SDR and HDR and somehow emulating HDR. We also discussed on the usage of a kernel background color property. Finally, we discussed a bit about Chamelium and the future of VKMS (future work and maintainership).

Power Savings vs Color/Latency Mario Limonciello (AMD) led this session. Mario gave an introductory presentation about AMD ABM (adaptive backlight management) that is similar to Intel DPST. After some discussions, we agreed on exposing a kernel property for power saving policy. This work was already merged on kernel and the userspace support is under development. Upstream work related to this session:

• Kernel series: Add support for power saving policy property (merged)
• Mutter: issue: support for power saving policy property
• Kwin: MR Draft: backends/drm: add support for the power saving policy property

Strategy for video and gaming use-cases Leo Li (AMD) led this session. Miguel Casas (Google) started this session with a presentation of Overlays in Chrome/OS Video, explaining the main goal of power saving by switching off GPU for accelerated compositing and the challenges of different colorspace/HDR for video on Linux. Then Leo Li presented different strategies for video and gaming and we discussed the userspace need of more detailed feedback mechanisms to understand failures when offloading. Also, creating a debugFS interface came up as a tool for debugging and analysis.

Real-time scheduling and async KMS API Xaver Hugl (KDE/BlueSystems) led this session. Compositor developers have exposed some issues with doing real-time scheduling and async page flips. One is that the Kernel limits the lifetime of realtime threads and if a modeset takes too long, the thread will be killed and thus the compositor as well. Also, simple page flips take longer than expected and drivers should optimize them. Another issue is the lack of feedback to compositors about hardware programming time and commit deadlines (the lastest possible time to commit). This is difficult to predict from drivers, since it varies greatly with the type of properties. For example, color management updates take much longer. In this regard, we discusssed implementing a hw_done callback to timestamp when the hardware programming of the last atomic commit is complete. Also an API to pre-program color pipeline in a kind of A/B scheme. It may not be supported by all drivers, but might be useful in different ways.

VRR/Frame Limit, Display Mux, Display Control, and more and beer We also had sessions to discuss a new KMS API to mitigate headaches on VRR and Frame Limit as different brightness level at different refresh rates, abrupt changes of refresh rates, low frame rate compensation (LFC) and precise timing in VRR more. On Display Control we discussed features missing in the current KMS interface for HDR mode, atomic backlight settings, source-based tone mapping, etc. We also discussed the need of a place where compositor developers can post TODOs to be developed by KMS people. The Content-adaptive Scaling and Sharpening session focused on sharpening and scaling filters. In the Display Mux session, we discussed proposals to expose the capability of dynamic mux switching display signal between discrete and integrated GPUs. In the last session of the 2024 Display Next Hackfest, participants representing different compositors summarized current and future work and built a Linux Display wish list , which includes: improvements to VTTY and HDR switching, better dmabuf API for multi-GPU support, definition of tone mapping, blending and scaling sematics, and wayland protocols for advertising to clients which colorspaces are supported. We closed this session with a status update on feature development by compositors, including but not limited to: plane offloading (from libcamera to output) / HDR video offloading (dma-heaps) / plane-based scrolling for web pages, color management / HDR / ICC profiles support, addressing issues such as flickering when color primaries don t match, etc. After three days of intensive discussions, all in-person participants went to a guided tour at the Museum of Extrela Galicia beer (MEGA), pouring and tasting the most famous local beer.

Feedback and Future Directions Participants provided valuable feedback on the hackfest, including suggestions for future improvements.

• Schedule and Break-time Setup: Having a pre-defined agenda and schedule provided a better balance between long discussions and mental refreshments, preventing the fatigue caused by endless discussions.
• Action Points: Some participants recommended explicitly asking for action points at the end of each session and assigning people to follow-up tasks.
• Remote Participation: Remote attendees appreciated the inclusive setup and opportunities to actively participate in discussions.
• Technical Challenges: There were bandwidth and video streaming issues during some sessions due to the large number of participants.

Thank you for joining the 2024 Display Next Hackfest We can t help but thank the 40 participants, who engaged in-person or virtually on relevant discussions, for a collaborative evolution of the Linux display stack and for building an insightful agenda. A big thank you to the leaders and presenters of the nine sessions: Christopher Cameron (Google), Harry Wentland (AMD), Leo Li (AMD), Mario Limoncello (AMD), Sebastian Wick (RedHat) and Xaver Hugl (KDE/BlueSystems) for the effort in preparing the sessions, explaining the topic and guiding discussions. My acknowledge to the others in-person participants that made such an effort to travel to A Coru a: Alex Goins (NVIDIA), David Turner (Raspberry Pi), Georges Stavracas (Igalia), Joan Torres (SUSE), Liviu Dudau (Arm), Louis Chauvet (Bootlin), Robert Mader (Collabora), Tian Mengge (GravityXR), Victor Jaquez (Igalia) and Victoria Brekenfeld (System76). It was and awesome opportunity to meet you and chat face-to-face. Finally, thanks virtual participants who couldn t make it in person but organized their days to actively participate in each discussion, adding different perspectives and valuable inputs even remotely: Abhinav Kumar (Qualcomm), Chaitanya Borah (Intel), Christopher Braga (Qualcomm), Dor Askayo, Jiri Koten (RedHat), Jonas dahl (Red Hat), Leandro Ribeiro (Collabora), Marti Maria (Little CMS), Marijn Suijten, Mario Kleiner, Martin Stransky (Red Hat), Michel D nzer (Red Hat), Miguel Casas-Sanchez (Google), Mitulkumar Golani (Intel), Naveen Kumar (Intel), Niels De Graef (Red Hat), Pekka Paalanen (Collabora), Pichika Uday Kiran (AMD), Shashank Sharma (AMD), Sriharsha PV (AMD), Simon Ser, Uma Shankar (Intel) and Vikas Korjani (AMD). We look forward to another successful Display Next hackfest, continuing to drive innovation and improvement in the Linux display ecosystem!

• Enabling Unified Kernel Image on Debian

Preparing for Key Enrollment Before enrolling our keys, we need to put the device in Secure Boot Setup Mode. Verify the status using the bootctl status command. You should see output similar to the following image:

  sudo ls /efi/loader/keys/chamunda
db.auth  KEK.auth  PK.auth

Signing the Bootloader Sign the systemd-boot bootloader with your new keys:

sbsign --key <path-to db.key> --cert <path-to db.crt> \
   /usr/lib/systemd/boot/efi/systemd-bootx64.efi

Install the signed bootloader using bootctl install. The output should resemble this:

Note

If you encounter warnings about mount options, update your fstab with the umask=0077 option for the EFI partition.

Verify the signature using sbsign --verify:

SecureBootPrivateKey=/path/to/db.key
SecureBootCertificate=/path/to/db.crt

sudo dpkg-reconfigure linux-image-$(uname -r)
# Repeat for other kernel versions if necessary

sudo dpkg-reconfigure linux-image-$(uname -r)
/etc/kernel/postinst.d/dracut:
dracut: Generating /boot/initrd.img-6.10.9-amd64
Updating kernel version 6.10.9-amd64 in systemd-boot...
Signing unsigned original image
Using config file: /etc/kernel/uki.conf
+ sbverify --list /boot/vmlinuz-6.10.9-amd64
+ sbsign --key /home/vasudeva.sk/Documents/personal/secureboot/db.key --cert /home/vasudeva.sk/Documents/personal/secureboot/db.crt /tmp/ukicc7vcxhy --output /tmp/kernel-install.staging.QLeGLn/uki.efi
Wrote signed /tmp/kernel-install.staging.QLeGLn/uki.efi
/etc/kernel/postinst.d/zz-systemd-boot:
Installing kernel version 6.10.9-amd64 in systemd-boot...
Signing unsigned original image
Using config file: /etc/kernel/uki.conf
+ sbverify --list /boot/vmlinuz-6.10.9-amd64
+ sbsign --key /home/vasudeva.sk/Documents/personal/secureboot/db.key --cert /home/vasudeva.sk/Documents/personal/secureboot/db.crt /tmp/ukit7r1hzep --output /tmp/kernel-install.staging.dWVt5s/uki.efi
Wrote signed /tmp/kernel-install.staging.dWVt5s/uki.efi

Enrolling Keys in Firmware Use systemd-boot to enroll your keys:

systemctl reboot --boot-loader-menu=0

Select the enroll option with your hostname in the systemd-boot menu. After key enrollment, the system will reboot into the newly signed kernel. Verify with bootctl: